Motor fuel



May 10, 1960 w. E. Lovr-:TT ET AL MOTOR FUEL Filed June` 12, 1957 Elbert D. Nostrclnd United States Patent O 2,936,223 Moron FUEL william 1i. Lovett, Plainfield, and Elbert D. Nosfrand,

Westfield, NJ., assignors to Esso Research and Engineering Company, a corporation of Delaware Application June 12, 1957, Serial No. 665,325

6 Claims. (Cl. 44-56) The present invention is concerned with an improved motor fuel composition adapted to provide improved engine performance in automotive vehicles, motor boats and aircraft in cool, moist atmospheric conditions under which icing due to freezing of atmospheric moisture nor- V -mally occurs. The motor fuel composition of the present invention comprises gasoline, which, as is well known, is essentially a hydrocarbon mixture having suitable volatility for operating internal combustion engines with spark-ignition, and containing as an ingredient a total of less than 2% by volume but suicient to decrease stalls due to icing of an aliphatic diol or mixture of diols of a particular type in critical combination with a volatile alcohol or mixture of alcohols.

In addition, the fuel compositions of the present invention may contain other additives', such as oiliness agents, gum solvents, alkyl-lead antidetonants, lead-scavenging agents, dyes, gum inhibitors, antioxidants, rust-preventives, metal-deactivators and the like, which are well known in the art as :desirable ingredients of gasoline for use as motor fuel. l

The diols in the fuel composition are similar to those described in U.S. 2,701,754, February 8, 1955, Motor Fuel, inventors, I. P. Haworth et al. The motor fuel of the present invention is of the type of that described in this patent.

The novel fuel compositions of this invention are primarily intended to overcome certain operational diiculties in connection with automotive, marine, stationary, and airplane engines. The diflculties referred to are caused by ice formed from moisture in the air in the intake system of an engine and result in frequent stalling of the engine under idling conditions when the circumambient `air has a relatively high humidity and is at a ternperature below about 60 F. This stalling phenomenon is now well known in the art.

It will be understood by those skilled in the art that the tendency of an engine to stall under cool, moist atmospheric conditions is in part a function of fuel volatility; i.e., an engine operating on a volatile fuel is more likely to stall under such atmospheric conditions than when operating on a less volatile fuel of similar composition. It will further be understood, therefore, that in a gasoline of relatively low volatility, lower total concentrations of the critical anti-stalling additive mixtures of this invention are required than in a more volatile gasoline to give satisfactory engine performance.

The fuel may be either aviation gasoline or motor gasoline. The volatilities of these gasolines in general vary over a range of vapor pressure at 100 F. from 6 lbs./sq. in. to lbs/sq. in. and over a range of 50% points, in ASTM D-86 tests, from 170 to 270 F. The ASTM end point of aviation gasoline is between 250 and 350 F.; and that of motor gasoline is between 350 and 450 F. Complete specifications for gasolines suitable to be used in accordance with the present invention motor gasoline are fully defined in Federal Specification VVM561 a-2 of October 20, 1954 as Fuel M,

2,936,223 Patented May 10, 1960 Regular and Premium grades of Classes A, B and C, and all the significant limits of volatility for motor gasoline to be used in accordance with the present invention are listed there. Also aviation gasoline is fully defined in U.S. Military Specifications MIL-F-5572-1 of July 20, 1950.

As pointed out above, the present invention is concemed with gasoline compositions containing a critical amount of diol, which is an aliphatic oxygen-containing compound having two hydroxyl groups, in combination with an alcohol.

The oxygen-containing compounds of the present invention are aliphatic diols, either saturated or unsaturated, containing from 4 to 21 carbon atoms per molecule. The preferred diols are characterized by having an alkyl radical directly attached to at least one of the carbon atoms to which a hydroxyl group is attached. The alkyl group may contain from 1 to 4 carbon atoms, although it is preferred that the alkyl group be a methyl group. Among the preferred diols, those having from 6 to 8 carbon atoms are most preferred, particularly, the hexylene glycols as, for example, 2methyl-2,4pentane diol, hexane diol-2,5 and 2-methyl-pentene-5-diol-2,4. Especially preferred among the hexylene glycols is 2- methyl-2,4pentane diol. Also useful but less eective than the foregoing are 1,3 dimethyl-butane-diol-2,3 and 2-methylpentanediol 1,3, which latter does not have the methyl group on the same carbon atom as either of the hydroxyl groups.

The alcohols are those containing from 1 to 3 carbon atoms, eg., methyl, ethyl, propyl, allyl and isopropyl alcohols. Especially preferred is isopropyl alcohol.

The amount of hexylene glycol employed will depend upon the amount of alcohol used. In general, the amount of hexylene glycol used will be in the range of from 0.01 to 0.095% by volume while the amount of alcohol as, for example, methyl alcohol or isopropyl alcohol should be in the range from about 0.40 to 1.8% by volume. In accordance with a particularly preferred embodiment of this invention, the concentration of the alcohol must not be less than 10 nor more than 30 times the concentration of the hexylene glycol. For example, in a gasoline `of relatively low volatility (eg. 50% at 270 F.), there is added 0.4% isopropyl alcohol together with 0.01 to 0.04% hexylene glycol. Similarly, in a gasoline of relatively high volatility, there is added 1.8% isopropyl alcohol, together with 0.06 to 0.095% hexylene glycol. In these two examples, best results are obtained when the volume ratio of alcohol to diol is 20/ 1.

In order to determine the effectiveness of the fuel compositions of the present invention, a number of tests were conducted on two 1956 Plymouth laboratory test engines. While the temperature and humidity were maintained at particular levels, the stalling characteristics of the engines were determined during the warm-up period. The procedure employed was to start the engine and then immediately to raise the engine speed to 1500 rpm.. This speed was maintained for 30 seconds, after which the engine was allowed to idle for 15 seconds. If the engine stalled before 15 seconds had expired, the engine was again started and the speed immediately raised to l5 00 r.p.m. for 30 seconds; while if stalling did not occur, the speed was increased to 1500 rpm. after the 15 seconds idling time. The alternate cycles lof 30 seconds at 1500 r.p.m. followed by 15 seconds at idling were repeated until the engine was completely warmed up. The number of stalls encountered by this procedure up to the time of complete engine warm-up was then recorded.

The base fuel was a premium grade of commercial gasoline, having a 10% ASTM distillation point of 117 F., a 50% point of 192 F. and a 90% point of 300 F. by ASTM Method D-86, which is the recognized method for measuring the volatility of gasoline. This gasoline also contained tetra-ethyl lead, scavenging agent and antioxidant, such as are conventional in the art. Various percentages of isopropyl alcohol (isopropanol) and hexylene glycol and mixtures thereof were tested in this common base fuel as shown in Table I.

Data obtained at 40 F. and 100% relative humidity. b 30 seconds at 1500 r.p.m., 15 seconds at idle. e 2methyl-2,-'1pentanediol.

The foregoing results are graphically illustrated in the drawing, which shows that the composition No. 6 (Table I) which is a preferred embodiment of the present invention, has outstanding and unexpectedly superior effectiveness for decreasing the number of stalls.

Other tests were carried out in three cars with another base fuel and with various proportions of the same glycol and alcohol. The results are shown in Table II.

TABLE II Additive evaluations in late model cars a [40 F., 100% relative humidity] Average Stalls in 25 Cycles Oar b Additives Number Percent Tone 21 100 2% isopropyl Alcohol 12 57 1956 Plymouth v-- 0.14% Hexylene Glycol 13 59 1.0% isopropyl Alcohol.. A 21 0.05% Hexylene Glycol Tone 16 100 2% isopropyl Alcohol- 0 0 1957 Ford 0.14% Hexylene Glycol. 0 0 1.0% isopropyl Alcohol d 0 o 0.05% Hexylene Glycol None 100 2% isopropyl Alcohol- 8 53 1957 Plymouth 0.14% Hexylene Glyco 7. 5 50 1.0% isopropyl Alcohol.. 3 20 0.05% Hexylene Glycol e Base fuel was a winter grade premium gasoline without anti-lclng additive, with volatility of 65% evaporated at 212 F. in ASTM D-8 and 13.5 lbs. Reid vapor pressure.

b All the cars contained V-S engines. Y

Equipped with a two barrel carburetor.

d Engine roughness was less than with 2% isopropyl alcohol or 0.14% hexylene glycol.

A cycle consists of 30 seconds at 1500 r.p.m. followed by 15 seconds at dllng speed.

These data show the outstanding eectiveness of a mixture of isopropyl alcohol and hexylene glycol in volume ratio of 20/1 for decreasing stalls by at least 66% and as much as or complete elimination of stalling.

To summarize, the preferred embodiment of the present invention is a motor fuel of the type of gasoline to which has been added a small but critical concentration, not exceeding 1.9% by volume, but suliicient to decrease stalls due to icing by at least 66% from the number of stalls obtained with the motor fuel alone, of a mixture of an alcohol having 1 to 3 carbon atoms per molecule and a hexylene glycol, eg., 2methyl2,4-pentane diol, in a volume ratio between 10 and 30 parts of said alcohol to l part of said glycol.

What is claimed is:

1. A gasoline having a vapor pressure between about 6 and about 15 pounds per square inch at 100 F. to which has been added about 1.0% by volume of isopropanol alcohol in conjunction with about 0.05 of an unsubstituted hexylene glycol.

2. A gasoline as defined by claim 1 wherein said hexylene glycol is 2-methyl-2,4pentane diol.

3. As a new composition of matter a gasoline having vapor pressure between 6 and 15 p.s.i. at 100 F. and 50% point in ASTM D-86 test between 170 and 270 F. and containing up to 1.9% by volume of a critical anti-stalling additive mixture of isopropyl alcohol and 2-methyl-2,4pentane diol, said alcohol being present in concentration between 0.4 and 1.8% by volume of said composition and in volume ratio between 10 and 30 to said diol.

4. The gasoline composition of claim 3' wherein the volume ratio is about 20.

5. The gasoline composition of claim 3 wherein the alcohol concentration is about 1%.

6. The gasoline composition of claim 5 wherein the volume ratio is about 20.

References Cited in the le of this patent UNITED STATES PATENTS 2,104,021 Callis Jan. 4, 1938 2,229,215 Magruder et al. Ian. 21, 1941 2,646,348 Neudeck July 21, 1951 2,701,754 Haworth et al Feb. 8, 1955 2,807,526 Foreman Sept. 24, 1957 FOREIGN PATENTS 555,193 Great Britain Aug. 10, 1943 766,591 Great Britain Jan. 23, 1957 

1. A GASOLINE HAVING A VAPOR PRESSURE BETWEEN ABOUT 6 AND ABOUT 15 POUNDS PER SQUARE INCH AT 100*F. TO WHICH HAS BEEN ADDED ABOUT 1.0% BY VOLUME OF ISOPROPANOL ALCOHOL IN CONJUNCTION WITH ABOUT 0.05% OF AN UNSUBSTITUTED HEXYLENE GLYCOL. 